People from vegetarian cultures may have different genes

Why is it that some people can stay healthy only by sticking to a strict vegetarian diet? Why is it that others can eat a steak a day, remain slim, avoid heart disease and feel like a million dollars? The answers may lie in your heritage.

Cornell University researchers have found a fascinating genetic variation that they say appears to have evolved in populations that favored vegetarian diets over hundreds of generations. The geography of the vegetarian allele, a variant form of a gene, includes people from India, Africa and parts of East Asia who are known to have green diets even today.

Researcher Kaixiong Ye said the vegetarian adaptation allows people to “efficiently process omega-3 and omega-6 fatty acids and convert them into compounds essential for early brain development.”

Omega-3 is found in fish, whole grains, olive oil, fruits and vegetables, while omega-6 is found in beef, pork products and many packaged snack foods such as cookies, candies, cakes and chips, as well as in nuts and vegetable oils.

Nutritionists believe that getting a good balance of these two types of fatty acids in the diet is essential to staying healthy.

Studies have suggested that humans evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids of 1:1 but that the Western diet has a ratio closer to 15 or 16:1. The Mediterranean diet, is closer to having an equal balance of the two and is recommended by many doctors.

But this new study, funded by the National Institutes of Health and the U.S. Department of Agriculture, shows that different people may need radically different ratios of the substances in their diet depending on their genes.

The existence of the vegetarian allele implies that, for people with this variation, straying from that diet — by eating a lot of red meat, for example — may make them more susceptible to inflammation, because their bodies were optimized for a different mix of inputs.

The research was published yesterday in the journal Molecular Biology and Evolution.

— The Washington Post